The decision follows heavy rains across both the south and north shores on Saturday that forced the early end to both the New Orleans Jazz Fest and the PGA Tour's Zurich Classic.

"In light of latest guidance and some recent trends, have decided to expand the flash flood watch to include the interior sections of the parishes south of the tidal lakes, and also run it through (7 p.m.)," forecasters said in a 10 p.m. update of a forecast discussion message.

"Widespread rainfall of 1 to 3 inches today have nearly saturated grounds across the watch area," forecasters said in a flash flood watch message. "A second round of storms will likely yield excessive water runoff and produce flooding."

Primary impacts will be flash flooding in low-lying areas, especially in urban areas with poor drainage and along low-lying rural roads.

The extended area includes all of New Orleans and upper portions of Lafourche, Jefferson, Plaquemines, St. Bernard and Terrebonne parishes and all of St. Charles Parish.

A flash flood watch is in effect until 7 p.m. Sunday for the North Shore and areas extending to the west and north of Baton Rouge, and east along the Mississippi Gulf Coast. National Weather Service

The watch also has been extended until 7 p.m. Sunday for the remainder of the forecast area, which extends from west of Baton Rouge across the North Shore and includes the Mississippi Gulf Coast.